In the refrigeration system of the refrigeration appliances, the gas under pressure which is pumped by the compressor is conducted to a heat exchanger (of the tube-wire or fin type), where the gas exchanges energy and suffers a change of state.
Generally, the fin type construction, as used for example in air conditioners, comprises a thermal exchange tube, which is in the form of parallel rectilinear portions communicating with each other by curved end portions, and in which circulates the refrigerant fluid. The thermal exchange tube is mounted in a structure formed by a plurality of flat plates or fins, which are parallel to each other and to the direction of a forced air flow, and which are orthogonal to the longitudinal axis of the rectilinear portions of the thermal exchange tube, said portions being disposed in rows or arrangements of the quincunx type, for example.
The provision of flat fins aims at increasing the area of thermal exchange with the thermal exchange gas, usually air, which flows between these fins. In order to improve the heat exchange between the air and the refrigerant fluid inside the thermal exchange tube, the flat fins may have constructive details on the surface thereof, usually in the form of fin projections stamped on the fin plate itself.
The thermal exchange mechanism in the case of the fins provided with fin projections results from phenomena, such as the successive interruptions and restartings of the limit layer, simulating a condition of constant heat input, with less thickness of the limit layer and a self-sustained oscillatory flow above a determined number of Reynolds.